Why Southeast Greenland's glaciers have slown down since 2005

I'm in San Francisco for the annual meeting of the American Geophysical Union, the world's largest gathering of climate scientists. I saw ten or so great talks yesterday (and five really boring ones!) Here's a summary of the the most interesting talk I heard yesterday:

If you plan on owning ocean front property after the year 2050, you should pay close attention to the glaciers In Greenland. Greenland holds enough ice to raise global sea level by over 20 feet (6.5 meters), should its ice cap completely disintegrate--though such an event would likely take centuries to occur. Still, should the climate warm 2°C or more this century, partial melting of the Greenland Ice Sheet could readily raise global sea level by a meter or more by 2100. That's why scientists reacted with concern during 2003 - 2005, when all of the glaciers in southeastern Greenland accelerated in synchrony to speeds 30% to 210% faster than they had flowed in 1996. As they sped up, the glaciers began dumping huge amounts of ice into the ocean off the coast of southeast Greenland, more than doubling Greenland's contribution to global sea rise, to .57 mm/year. Would the glaciers keep accelerating, bringing about an increasing disintegration of the Greenland Ice Sheet? Nobody knew, since computer models of glacial dynamics were (and still are) in a primitive state.

Figure 1. Helheim Glacier in southeast Greenland, in three images captured in 2004, 2005, and 2006. The glacier accelerated significantly in 2005, and the face of the glacier retreated 5 km inland (middle frame) compared to 2004. However, by the summer of 2006, the acceleration ceased, the the glacier returned back to its 2004 position. Image credit: Ian Howat, University of Washington.

Well, it turned out that 2005 was the peak of the glacial acceleration event. The glaciers in southeast Greenland have returned to where they were eight or nine years ago--still causing a net loss of mass that is raising global sea level, but not as fast as in 2003 - 2005. In a talk titled, "Ocean regulation of glacier dynamics in south-east Greenland and implication for ice sheet mass changes",Tavi Murray and colleagues from the UK's Swansea University presented a plausible theory for why this strange synchronous speed-up and slow-down occurred. Using satellite, aircraft, and surface observations, the researchers found that air temperatures in the region did not vary much over 2003 - 2005 (Figure 2). Thus, a major increase in temperature could be ruled out as the cause of the glacier surge. However, study of the ocean temperatures near the coast revealed strong clues that ocean currents were responsible for the surge.Figure 2. Ocean currents off the east coast of Greenland feature the cold East Greenland Coastal Current flowing north to south (white arrows) and the warm Irminger Current flowing south to north (red arrows). Image credit: Arctic Climate Impact Assessment.

Ordinarily, the southeast coast of Greenland features a cold water current flowing north to south, called the East Greenland Coastal Current (EGCC). Much of the cold water for this current is supplied by melting of the 14 glaciers in southeast Greenland that empty into the sea (two of these glaciers, Kangerdlugssuaq and Helheim, represent 35% of east Greenland's total glacial discharge). A few hundred kilometers offshore, a warm water current called the Irminger Current flows the opposite direction, bringing warm water from the North Atlantic northward. In 2003, it happened that weather conditions over Greenland brought an unusually low amount of run-off of precipitation. With little new mass pushing the glaciers seaward, the glaciers responded by greatly reducing the amount of ice they dumped into the ocean by the shore. As a result, the East Greenland Coastal Current slowed down and warmed, which allowed the warm Irminger Current to advance towards the coast, warming the coastal waters even more. All that warm water near the coast began melting the glaciers where they reached the sea, causing the glaciers all along the southeast coast of Greenland to accelerate and rapidly thin between 2003 - 2005. By 2006, the thinning glaciers had dumped so much new ice into the ocean near the coast that the waters cooled and the East Greenland Coastal Current re-established itself. This cooled the glaciers at their marine termination points and slowed down the glacial surge, putting the glaciers back where they had been before 2003. This is a classic example of a negative feedback process--a change in weather conditions which generates a response, but the response creates conditions that tend to dampen the response.

Figure 3. Average temperatures for the only station in southeast Greenland with a century-long temperature record, Angmagssalik (called Ammassalik on the map in Figure 2). Temperatures in southeast Greenland during the 1930s and 1940s were similar to today's temperatures, suggesting that glacial surges like we witnessed in 2005 may have also occurred in the 1930s and 1940s, before we had monitoring capability. Image credit: NASA Goddard.

CommentaryAs I commented in my previous post, Arctic sea ice loss appears to have created a new atmospheric circulation pattern that brings more warm air in the Arctic, creating a positive feedback loop that causes even more sea ice loss. This positive feedback loop was a bad news surprise that our climate models did not predict. Now we have evidence of a good news surprise that no model predicted--a negative feedback loop that acts to keep the southeast portion of Greenland's Ice Sheet from runaway glacial acceleration. We can expect many more surprises--good and bad--over the coming decades, as our climate responds to the huge shove human activities are giving it.

Ricky Rood in CopenhagenOur Climate Change expert, Dr. Ricky Rood, is in Copenhagen for the COP15 climate change treaty negotiations. His latest post, called Have you no sense of decency, sir, at long last? makes for very interesting reading on how the U.S. is "wasting its intellect and time on disruptions designed to play to people at home".

Next postI'll have another post from the AGU meeting Thursday or Friday this week.

Mid Atlantic states in the inland areas particularly in South or North Carolina (also around the Appalachians) may see the heaviest snow and perhaps some light snow around the coastal area of those states depending on the track of the low and the cold air advection.

Drakoen, Do you see any snow for the Tennessee Valley? Some models show a stormy period from the 24th until the end of the month.

At 2:00 am WST, Severe Tropical Cyclone Laurence, Category 4 (954 hPa) located at 15.0S 124.5E has 10 minute sustained winds of 90 knots with gusts of 125 knots was estimated to be 55 kms north of Kuri Bay and 155 kms northeast of Cockatoo Island and moving southwest at 5 knots.

Hurricane Force Winds====================15 NM from the center

Storm Force Winds=================20 NM from the center

Gale Force Winds===============40 NM from the center in southern quadrant45 NM from the center in northeastern quadrant50 NM from the center in northwestern quadrant

Dvorak Intensity: T5.5/5.5/D1.5/ 24HRS

Severe Tropical Cyclone Laurence is a small but intense tropical cyclone having VERY DESTRUCTIVE WINDS with gusts to 230 kilometres per hour close to the cyclone centre. As Laurence tracks to the southwest near the Kimberley coast VERY DESTRUCTIVE winds may develop at Kuri Bay during Wednesday morning.

GALES with gusts to 100 kilometres per hour should extend further southwest along the coast, reaching Cockatoo and Koolan Islands during Wednesday and should the centre pass close by VERY DESTRUCTIVE winds are possible during the afternoon and evening. GALES may extend to Derby and Beagle Bay overnight Wednesday.

HEAVY RAIN is expected to continue over the north Kimberley region, extending into the western Kimberley during Wednesday. Daily rainfall totals in excess of 100mm are possible near the coast with totals decreasing further inland.

Tropical Cyclone Watches/Warnings==================================A Cyclone WARNING is current for coastal areas from Mitchell Plateau to Beagle Bay.

Additional Information======================Laurence is a small but intense system, as demonstrated by the observations at Troughton Island on Tuesday morning, where a peak gust of 185 km/h was measured as the system went directly over the island. An eye is evident on IR and microwave imagery . Recent EIR images produced a DT of 5.5-6.0. While DT may suggest 6.0 based on surround CMG [-0.5 eye adjustment CDG/B], the FT is set at 5.5 in agreement with the PAT.

Laurence has intensified under favourable upper level outflow and low shear but despite being in close proximity to land. Intensity is maintained at 90 knot mean winds for next 12-18 hours as it tracks parallel to the coast, but intensity is heavily dependent upon the influence of land. Most models suggest landfall is the most likely scenario by about +18-24 hours and weakening is then likely as a more southerly track ensues.

A more westerly track is possible beyond +48 hours and potentially the system may move offshore and redevelop in the longer term.

...."In fact, to date this experiment in combining disparate elements has been a horrendous and costly failure," the committee report said. Appropriators cited a dysfunctional relationship among NOAA, NASA and the Pentagon, the three partners in the NPOESS program, and encouraged NOAA to study contingency options to ensure there is no data gap from polar satellites.

Mid Atlantic states in the inland areas particularly in South or North Carolina (also around the Appalachians) may see the heaviest snow and perhaps some light snow around the coastal area of those states depending on the track of the low and the cold air advection.

Hmmmm a Cedar Key/St. Augustine track would give us a lot of rain. But that track would be further north than any track that has given us accumulating snow.

I wonder how deep the low will be.

Mid Atlantic states in the inland areas particularly in South or North Carolina (also around the Appalachians) may see the heaviest snow and perhaps some light snow around the coastal area of those states depending on the track of the low and the cold air advection.

The question is, would I be a problem for THEM?(not sure how to put that delicately...but it's that special time of year for latkes and, everybody sing along now -- dreidel, dreidel, dreidel, I made it out of clay...)

Also, I think you may have a Masters Degree? certainly advanced certifications...that made you no. 1 most edjumicated in town during family reunions! Was that specially warm and fuzzy??

AND, having the prisoners do honest work and good deeds is excellent karma-repairing mechanism!!

Quoting atmoaggie:Yep. That isn't good:St. Charles Parish jail trusties and parish employees sandbag the top of the Magnolia Ridge levee that was overtopped by water Tuesday, December 15, 2009 in Boutte.

(And, AIM, my great-great-great aunt Myrt lived in Boutte for 96 years, until she passed away last year. We had a labor day picnic at her place every year. Some great memories. Is that a problem for you?)

The question is, would I be a problem for THEM?(not sure how to put that delicately...but it's that special time of year for latkes and, everybody sing along now -- dreidel, dreidel, dreidel, I made it out of clay...)

Also, I think you may have a Masters Degree? certainly advanced certifications...that made you no. 1 most edjumicated in town during family reunions! Was that specially warm and fuzzy??

AND, having the prisoners do honest work and good deeds is excellent karma-repairing mechanism!!

The exact glacier region in Southeastern Greenland mentioned in the blog is currently experiencing temperatures near 11C (52F) near the mouth of the fjord at the end of the glacier, according to Wunderground SST (sea surface temperature) maps.

Quoting Drakoen:Couple of interesting things shaping up for this weekend and next weekend. Teleconnections still show a positive PNA, and strongly negative AO, and a negative NAO. The cold front looks to descend into the Gulf of Mexico Wednesday morning. A low pressure system looks to slowly develop in the baroclinic zone in the western GOM and move eastward over though Friday bringing with a a shield of rain into Louisiana then spreading into Florida. Rainfall totals highest along the coastal areas between 1-2 inches. After the low pressure system crosses Florida the big question is where will it go. The 12z GFS ensemble members have come a bit farther westward with the track of the low pressure system but still remain on the eastern side of the guidance with the ensemble mean taking the system away from the coastline. The operational GFS has come more into agreement with the ECMWF track and timing of the system near the eastern seaboard which would bring heavy snow to the mid Atlantic states and Appalachians; the northeast, if the ECMWF solution pans out, could see decent snow with the deformation axis stretching towards the Great Lakes. The 00z GGEM shows a reasonable solution similar to the aforementioned models compared to its 12z run.

High pressure behind the low will lead to cold and dry conditions.

What is your best guess for landfall in Florida? It was said earlier central / SW Florida.

Couple of interesting things shaping up for this weekend and next weekend. Teleconnections still show a positive PNA, and strongly negative AO, and a negative NAO. The cold front looks to descend into the Gulf of Mexico Wednesday morning. A low pressure system looks to slowly develop in the baroclinic zone in the western GOM and move eastward over though Friday bringing with a a shield of rain into Louisiana then spreading into Florida. Rainfall totals highest along the coastal areas between 1-2 inches. After the low pressure system crosses Florida the big question is where will it go. The 12z GFS ensemble members have come a bit farther westward with the track of the low pressure system but still remain on the eastern side of the guidance with the ensemble mean taking the system away from the coastline. The operational GFS has come more into agreement with the ECMWF track and timing of the system near the eastern seaboard which would bring heavy snow to the mid Atlantic states and Appalachians; the northeast, if the ECMWF solution pans out, could see decent snow with the deformation axis stretching towards the Great Lakes. The 00z GGEM shows a reasonable solution similar to the aforementioned models compared to its 12z run.

In the Long range the ECMWF shows a strong long-wave trough and high pressure system advection from Canada in contrast to the GFS buckling things north of the Tennessee river valley.

Quoting whosonfirst:In fact, the new research, by NASA's William Lau and collaborators, reinforces with detailed numerical analysis what earlier studies suggest: that soot and dust contribute as much (or more) to atmospheric warming in the Himalayas as greenhouse gases. This warming fuels the melting of glaciers and could threaten fresh water resources in a region that is home to more than a billion people.

Lau explored the causes of rapid melting, which occurs primarily in the western Tibetan Plateau, beginning each year in April and extending through early fall. The brisk melting coincides with the time when concentrations of aerosols like soot and dust transported from places like India and Nepal are most dense in the atmosphere."http://www.nasa.gov/topics/earth/features/himalayan-warming.html

You left out a paragraph that might help put this into better perspective:

"Over areas of the Himalayas, the rate of warming is more than five times faster than warming globally," said William Lau, head of atmospheric sciences at NASA%u2019s Goddard Space Flight Center in Greenbelt, Md. "Based on the differences it%u2019s not difficult to conclude that greenhouse gases are not the sole agents of change in this region. There%u2019s a localized phenomenon at play."

Not saying this isn't significant but this study just applies to the Tibetan Plateau, correct?

Yes, I left out a lot of the article. Didn't want to take up too terribly much space.

This study does apply only to the Tibetan Plateau. Others have been conducted for other places.

Are you implying that soot might have 5 times the effect of GHGs there rather than a 1 to 1 ratio (as the "as much" implies)? We really are working on the wrong problem. Good point.

Yep. That isn't good:St. Charles Parish jail trusties and parish employees sandbag the top of the Magnolia Ridge levee that was overtopped by water Tuesday, December 15, 2009 in Boutte.

(And, AIM, my great-great-great aunt Myrt lived in Boutte for 96 years, until she passed away last year. We had a labor day picnic at her place every year. Some great memories. Is that a problem for you?)

For those of us who think we like winter and those who know they don't - this is the response from a friend of mine in Edmonton for Christmas after I asked her about the -46*C record (having sent wu post 1396. toontown 8:16 PM GMT on December 14, 2009:Yep - they shut the airport down just after my plane got in on Saturday night because it was too cold for the ground crews to work. But Lois and I have gotten out for a good walk every morning in spite of the cold. Today should feel downright balmy -- we're going up to -23.

So, we had a bit of excitement in here a number of days ago about the Himalayas, warming, and glacier melt...

Well, NASA says half of that melt, or more, may be due to soot deposition.

"A new modeling study from NASA confirms that when tiny air pollution particles we commonly call soot, also known as black carbon, travel along wind currents from densely populated south Asian cities and accumulate over a climate hotspot called the Tibetan Plateau, the result may be anything but inconsequential.

In fact, the new research, by NASA's William Lau and collaborators, reinforces with detailed numerical analysis what earlier studies suggest: that soot and dust contribute as much (or more) to atmospheric warming in the Himalayas as greenhouse gases. This warming fuels the melting of glaciers and could threaten fresh water resources in a region that is home to more than a billion people.

Lau explored the causes of rapid melting, which occurs primarily in the western Tibetan Plateau, beginning each year in April and extending through early fall. The brisk melting coincides with the time when concentrations of aerosols like soot and dust transported from places like India and Nepal are most dense in the atmosphere."http://www.nasa.gov/topics/earth/features/himalayan-warming.htmlCurrently at a state of modeling, admittedly.

But, given this, the fact that NASA has other studies showing soot to be responsible for up to half of Arctic sea ice melt (with wind patterns, ocean currents, ocean temps, and atmospheric temps responsible for the rest), and that we well know that others, like Kilimanjaro have their own equally local causes, is it really possible to assign as much blame to CO2 to these phenomena as we, collectively, are trying to?

Additionally, soot emission control is a far more easy fix with a far more immediate impact. And is a pollutant tied directly to incomplete burning and it, and the other byproducts produced along with it, do have direct, negative health effects.

So, in light of the great big political gorilla-in-the-room of CO2 governing, why would we not take a path of far less resistance and do something real about soot emissions when the impact in the Arctic, the Himalayas, Greenland (probably), etc. could have as much, or more (IMO) of an earth "back-to-normal" effect than any other single thing we could do?

Methinks we might be barking up a very tall small tree when we could be barking up a bigger tree with low-hanging branches...